Sometimes the only place to find your German immigrant ancestor is in the local German papers -- or my index of those papers called "Milwaukee's German Newspapers; an index of death notices and related items" (1844-1950).
There are multiple family death notices for Gottfried Grober, and also multiple notices that were published in 1850 by a Gottfried Grober to help recover his lost livestock (?!?). These could be matched to your ancestor by the address listed in the notice. (I have a personal fondness for these notices ;-)
Contact me for more information.
gary.rebholz@gmail.com